There has been known a pump using a diaphragm having a piezoelectric element bonded to a surface of a sheet metal. as a fluid driving element The pump has a housing comprising first, second and third housing members stacked on one another. The diaphragm is stretched between the first and second housing members to form a pump chamber between the diaphragm and the second housing member. The second housing member is provided with a fluid suction opening and a fluid discharge opening that open on a side surface thereof. The fluid suction opening and the fluid discharge opening are communicated with the pump chamber through respective check valves. Thus, a fluid is sucked into and discharged from the pump chamber by vibrating the diaphragm. In addition, a partition is provided between the second and third housing members to form an inlet chamber and an outlet chamber on the second housing member side and pulsation absorbing chambers on the third housing member side. More specifically, the inlet chamber is formed between the fluid suction opening and the pump chamber. The outlet chamber is formed between the fluid discharge opening and the pump chamber. The pulsation absorbing chambers are formed to face the inlet chamber and the outlet chamber, respectively, across the partition (see Patent Document 1).
The diaphragm used in this type of pump is a bimorph diaphragm having piezoelectric elements bonded to both sides of a sheet metal. The diaphragm is entirely covered with silicon to ensure electrical insulating properties.
Patent Document 1: Japanese Patent Application Publication No. 2000-265963